Stitch cam assembly for circular knitting machines and method of drawing elongated stitches



June 21, 1966 w. w. STURDIVANT, sR 3,256,717

STITCH CAM ASSEMBLY FOR CIRCULAR KNITTING MACHINES AND METHOD OF DRAWING ELONGATED STITCHES Filed Oct. 12, 1964 5 Sheets-Sheet l z a ll I /k.--" fi. j\ o INVENTOR BY ,finw

ATTORNEY WILLIAM W. STURDNANT SR.

June 1965 w. w. STURDIVANT, SR ,7 7

STITCH CAM ASSEMBLY FOR CIRCULAR KNITTING MACHINES AND METHOD OF DRAWING ELONGATED STITCHES Filed Oct. 12, 1964 5 Sheets-Sheet 2 INVENTOR WILLIAM W. STURDWANT Sn.

ATTORNEY Fig.3.

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STITCH CAM ASSEMBLY FOR CIRCULAR KNITTING MACHINES AND METHOD OF DRAWING ELONGATED STITCHES Filed Oct. 12, 1964 5 Sheets-Sheet 5 Fig. 5

INVENTOR 53 WHJJAM W STURD\VANT S R,

ATTORNEY United States Patent STITH CAM ASSEMBLY FOR CIRCULAR KNIT- TING MACHINES AND METHUD OF DRAWING ELQNGATED STITCHES William W. Sturdivant, Stu, Rte. 1, Danton, N.C. Filed Oct. 12, 1964, Ser. No. 403,303 11 Claims. (Cl. 66--54) This invention relates to means for varying the length of the stitch loops drawn by the needles of a circular knitting machine.

Circular knitting machines of the type with which the present invention is adapted to be associated are provided with a circularly arranged series of cylinder needles positioned for vertical sliding movement in slots in a needle cylinder and radially movable sinker positioned between the cylinder needles. During knitting, the needle cylinder is revolved, the needles raised to receive yarn in their hooks, and then the needles are successively lowered to stitch drawing level by stitch cams, the length of the stitch loops drawn depending upon the distance the hooks of the needle are drawn beneath the sinkers when the stitches are drawn.

Conventional knitting machines include means for varying the length of stitches to a limited extent, the variation in stitch length being conventionally accomplished by one of two methods, i.e. (1) raising or lowering the stitch cam assembly relative to the needle assembly to correspondingly vary the distance the needles are lowered beneath the sinkers after engaging the yarn in the hooks of the needles, or (2) raising or lowering the needle cylinder and sinkers relative to the stitch cam assembly. In either method, the length of the stitch is controlled by varying the vertical distance between the sinkers and the point at which the stitch is formed by depressing the needle.

The amount of stitch length variation which is possible in the conventional method first above described has been quite limited because of the fact that the entire stitch cam assembly is conventionally moved as a unit relative to the needle cylinder. The extent of such movement has been limited because of the necessity of maintaining the center stitch cam at a sufficiently high elevation to engage and direct the butts of successive needles under either the left or right hand stitch cam to draw down successive needles to stitch forming position. Although the stitch cam assembly is capable of a wide range of movement to infinitely vary the length of stitches in response to pattern control mechanism, excessive movement of the stitch cam assembly causes the clearing cam to direct the needle butts into the body of the center cam where the butts are bent or broken instead of presenting them to the inclined face of the center cam which draws the butts down and under the stitch cam.

The limited variations in stitch length possible according to the conventional practice just described are helpful at selected points throughout the circularly knitted fabric to give some shape to knitted articles such as hosiery and to define a looper line adjacent the toe portion of hosiery. But the limitations on stitch length prevent the drawing of stitches long enough, for example, to knit a satisfactory elastic cuif for hosiery utilizing an elastic strand.

Various means and methods have been devised for increasing the variation of stitch length beyond the variation possible according to the conventional practice, the disclosures of Patents 2,420,771, 2,716,876 and 3,013,414 being exemplary. In each instance, some change or modification of the normal knitting cycle is employed to increase .the stitch length, such as manipulating the sinkers, or knitting on top of the sinkers, or selectively introducing an auxiliary cam beneath the level of the stitch cam. These prior devices have all required modifications of varying degrees of complexity and expense to existing knitting ma- 3,256,717 Patented June 21, 1966 chines, and in some instances a change of parts is necessary when it is desired to change the length of the long stitches being drawn. In other words, such prior devices are capable of drawing elongated stitches of only a single predetermined length depending upon the dimensions of the parts employed to draw the long stitches.

With the foregoing in mind, it is an object of this invention to provide a device for varying the length of stitches in a knitted fabric by utilizing the conventional and existing mechanism and knitting cycle of a circular knitting machine such as disclosed, for example in Hemphill Patent No. 933,443, it being possible through use of the present invention to vary the length of the stitch either. a small or large amount as desired responsive to the conventional pattern control mechanism in the conventional manner without the need for any additional control or selector means and while permitting the knitting machine to function in its conventional manner.

A more specific object of the invention is to provide means for varying the length of stitches in a knitted fabric which utilizes the conventional pattern controlled cam means for varying the vertical movement of the cam plate relative to the sinker bed and wherein means are provided for supporting the center cam at substantially a constant distance from the sinker bed while raising and lowering the stitch and clearing cams relative to the sinker bed varying amounts in the conventional manner responsive to the pattern control device.

A further object of this invention is to provide a method and means for utilizing the existing pattern control mechanism and the conventional stitch cam on circular knitting machines to vary the length of stitches an infinite amount within broad ranges and without down time, the means of the invention being of simple inexpensive construction which may be easily applied to existing circular knitting machines without extensive modification.

According to the present invention, the length of stitches in a knitted fabric is varied as desired by effecting relative movement between the stitch and clearing cams and the center cam whereby the center cam may carry out its accustomed function of receiving the butts of the needles from the clearing cam and guiding the butts under the stitch cam which has been lowered by the pattern control mechanism to depress the needles sufficiently to make stitches of a desired length. One embodiment of the invention capable of carrying out the foregoing objects and purposes of the invention is illustrated in the accompanying drawings wherein:

FIGURE 1 is a side elevation of a circular knitting machine with which the present invention is adapted to be associated;

FIGURE 2 is an enlarged vertical sectional view through the needle cylinder and associated parts with parts broken away and looking in the same direction as FIGURE 1 showing the stitch cam and center cam in the positions they occupy during normal knitting;

FIGURE 3 is a sectional view similar to FIGURE 2 but omitting a portion of the needle cylinder and illustrating in an exaggerated manner the relative movement between the stitch cam and the center cam as the stitch cam is depressed to draw along stitch;

FIGURE 4 is a view taken substantially along the line 4-4 in FIGURE 2 but omitting the needle cylinder for purposes of clarity to show the stitch cam assembly in F elevation;

FIGURE 5 is an exploded view of a top center cam modified according to the present invention and illustrating its assembly with its supporting structure;

FIGURE 6 is a schematic development of the needle cams which control movement of the needles and showing in dotted lines the positions occupied by the stitch cam, center cam and clearing cam while making long stitches.

Although the present invention is shown in the drawings and described herein as being associated with a circular independent knitting machine of substantially the type shown in Patent No. 933,443 to Hemphill, it may be adapted to other types of knitting machines.

The knitting machine with which the present invention is adapted to be associated includes legs which support a frame 11 on which a conventional pattern control mechanism schematically illustrated at 12 is suitably supported. The frame 11 also supports a bed plate 13 on which a needle cylinder 14 is mounted for rotation on a vertical axis, rotation being imparted to the needle cylinder 14 through conventional gearing and driving mechanism, not shown.

The needle cylinder is grooved longitudinally of its axis to receive knitting needles 15 having laterally extending butts 15 projecting beyond'the periphery of the needle cylinder 14 for successive engagement with the cams of a stitch cam assembly broadly indicated at and including a left stitch cam 21, a center cam 22, and a right stitch cam 23. These cams are supported on a cam block 24 which defines a stitch drawing or knitting station and is supported by a cam plate 25 surrounding the needle cylinder 14 and which is in turn supported on the upper end of a vertically reciprocable connecting arm or post 26 which penetrates the bed plate 13 and is operatively connected to the conventional pattern control mechanism 12, which may be of the type as shown, for example, in

Patent No. 2,135,185. A needle cam ring 27 is suitably secured to the cam plate 25 and surrounds the needle cylinder 14 to guide the lowermost surface of the needle butts 15'.

The invention is applicable for use with machines equipped to knit elastic fabric as well as with machines adapted to knit plain fabric, and if desired, the usual elastic yarn feed cams, including needle lowering cams and a jack raising cam, not shown, may be provided to cooperate with the needles and jacks positioned beneath alternate needles so that these needles are raised to receive an elastic yarn from an elastic yarn feeding finger positioned to move into and out of yarn feeding position in a conventional manner.

The upper end of the needle cylinder 14 supports a sinker bed 30 slotted for reception of sinkers 31. A sinker 31 is positioned beside each needle in the cylinder 14. The sinkers 31 have radial sliding movement in slots of the sinker bed and slots in the upper end of the cylinder 14. The radial position of the sinkers 31 relative to the needle cylinder 14 is controlled by cams in a sinker cap 32. The sinker bed 30 is fixed to the upper end of the needle cylinder 14 in the usual manner and will rotate and reciprocate with the needle cylinder 14 while the sinker cap 32 is held in a substantially fixed position during knitting.

Referring to FIGURE 6, as the needles 15 pass from right to left through the knitting station, they are raised by the clearing cam 23 to shed the loops, after which yarn is fed to the needles 15 as they are lowered through successive engagement of their butts 15' with the center cam 22. The center cam 22 directs the needles beneath the left hand stitch cam 21 to draw stitches of a desired length as determined by the pattern control mechanism, after which the needles are raised by the inclined surface 33 of the cam ring 27. conventionally, the cams 21, 22 and 23 on the cam block 24 move as a unit relative to the sinker bed 30 in response to the pattern control mechanism to draw stitches of varying length in different portions of the fabric being knitted.

The apparatus and method of operation described above is conventional and, except for the structure of the cam assembly, forms a part of the knitting machine with which the present invention is adapted to be associated. While such a knitting machine includes many other parts and would require a much more lengthy explanation to describe its operation in detail, it is believed that the foregoing explanation will suffice for an understanding of the environmental setting of the invention.

According to the invention, the length of stitches drawn may be varied infinitely within broad ranges through the provision of means which will permit relative movement between the center cam 22 and the remainder of the cam assembly 20 whereby the stitch cam 21 may be lowered or raised to the extent necessary to draw the desired length of stitch while maintaining the center cam at substantially a constant level to move successive needles to yarn engaging position. This is accomplished through a modification of the center cam which heretofore, in the conventional cam assembly, was securely fastened to the cam block and movable therewith and with the cam 21 in response to reciprocation imparted to the arm 26 by the pattern mechanism.

Briefly, the modification of the center cam according to the invention comprises means for pivotally connecting the outer or rear end portion of the center cam 22 to the cam block 24 and means for supporting the medial portion of the center cam 22 directly upon the bed plate 13 and independently of the cam block 24 and cam plate 25. The inclined faces or cam surfaces on the forward or inner portion of the cam 22 traversed by the needle butts 15' are of sufiicient length to extend beyond the proximal edge of the stitch cam 21 when it is moved away from the center cam sufficiently to draw the longest stitch to be drawn during knitting.

Referring to FIGURE 5, the center cam of the present invention includes a body portion having a shoulder 40 extending transversely of its mid-portion to define a relatively narrow forward portion 41 and a thicker rear portion 42. The free end of the rear portion 42 is bifurcated to define legs 43 and a slot 44 for the reception of a mounting block 45 straddled by the legs 43. The block 45 has a first transverse bore 46 adapted to register with mating bores 47 in the legs 43 and through which a pivot pin 48 extends to pivotally connect the cam 22 to the mounting block 45. The block 45 includes a second transverse bore 49 extending at right angles to the bore 46 and communicating with a threaded bore 52 in the cam block 24. The mounting block 45 is secured to the cam block 24 by a bolt 53 enetrating the bore 49 and threaded into the bore 52 in the cam block 24.

The cam block 24 also has a bore 54 which extends at right angles to the bore 52 and communicates with the lower surface of the forward portion of the cam 22. The bore 54 is loosely penetrated by an axially adjustable support rod 55, the upper end of which bears against and supports the cam 22.- The support rod 55 also loosely penetrates the cam plate 25 and the lower end of the support rod 55 rests on the bed plate 13. The lower end portion of the rod 55 is preferably defined by a sleeve 55' provided with a set screw by means of which the effective length of the rod 55 may be adjusted.

The cam 22 is urged into engagement with the upper end of the support rod 55 by a spring 56 which surrounds a shaft 57 threaded into the upper surface of the cam block 24 and provided with an axially adjustable boss 58, the spring 56 extending between the boss 58 and the forward or inner portion of the cam 22 to normally urge the cam 22 away from the boss 58 and into engagement with the support rod 55.

In FIGURE 2 the center cam 22 and the stitch cam 21 are shown in the positions they occupy during normal knitting, that is, while the machine is knitting stitches of a conventional variation in length. The center cam 22 rests on top of the block 24 at a proper level to draw successive needles into yarn engaging position and to then direct them beneath the stitch cam to make stitches of normal length.

In FIGURE 3, the cam block 24 has been moved downwardly by the arm 26 in response to the pattern mechanism and has drawn with it the stitch cam 21 to draw long stitches. The center cam 22 is supported by the support rod 55 at substantially the same position as shown in FIGURE 2 although the cam block 24 has moved away from the center cam 22 carrying with it the outer or rear end portion of cam 22. As the block 24 moves downwardly, the cam 22 pivots about the pin 48 by which it is connected to the mounting block 45 causing a slight upward movement of the front or inner end portion of cam 22. The location of the support rod 55 at the forward portion of the center cam 22 minimizes pivotal upward movement of the forward portion of cam 22 so that the cam faces of the center cam 22 are maintained at substantially the same elevation or level in both FIG- URES 2 and 3 where they can continue moving successive needles to yarn engaging position and to direct them under the stitch cam 21.

The amount of movement of the cam block 24 and its stitch cam 21 relative to the center cam 22 illustrated in FIGURE 3 is exaggerated for purposes of illustration and in actual practice the cam block 24 probably will not move away from the center cam 22 to the extent illustrated. In any event, the amount of movement of the stitch cam 21 relative to the center cam 22 is limited by the fact that the proximal edge of the stitch cam 21 must remain above or at the level of the lowermost extremity of the cam faces on the center cam 22 so that the center cam 22 can effectively direct the needle butts beneath the stitch cam 21.

As previously indicated, the cam faces of the center cam 22 are lengthened to extend beyond the proximal edges of the stitch cams depending upon the length of stitch desired to be drawn and to compensate for the slight upward movement of the inner end of cam 22 as block 24 drops. An elongation of the inclined faces of the cam 22 of approximately one quarter inch more than the length of the faces on conventional center cams has been found satisfactory for knitting elastic top hosiery.

In FIGURE 6, the relative positions of the center cam 22 and the left and right hand stitch cam 21, 23 during normal knitting are shown in solid lines. Relative movement of these cams to draw long stitches is indicated by their dotted line positions. Of course, the cam ring 27' is depressed the same amount as the stitch earns 21, 23 when the cam plate 25 is lowered to draw long stitches. Since the bed plate 13 remains stationary, the center cam 22 is enabled through the support rod 55 to remain in the path of the needle butts 15' and perform its conventional function even though the remainder of the cam block 24 and ring 27 have been dropped to draw long stitches.

When it is desired to draw stitches of less than nor- -mal length, the center cam 22 is supported on top of block 24 and moves upwardly with the remainder of the cam assembly in response to the pattern control mechanism in a conventional manner.

There is thus provided an improved method and means of infinitely varying the length of stitches in a knitted fabric through relative movement of the cams in the stitch cam assembly while enabling the knitting machine to carry out its normal knitting steps in the conventional manner.

In the drawings and specification there have been set forth preferred embodiments of the invention and, although specific terms are employed, they are used in a generic and descriptive sense only and not for purposes of limitation, the scope of the invention being defined in the claims.

I claim:

1. -In a circular knitting machine having a plurality of reciprocable needles and sinkers cooperating with each other for the formation of stitches to define a knitted fabric, said knitting machine also including a bed plate, a cam ring, pattern control mechanism and a stitch cam assembly operative at selected points during the knitting of the fabric to vary the length of stitches in the fabric, said knitting machine also including a cam block from which the stitch cam and center cam project into the path of the needles and a connecting arm extending between the pattern control mechanism and the cam ring, the combination of means for effecting relative movement between the stitch cam and the center cam, comprising:

(a) means connecting the stitch cam to the cam block for movement with said connecting arm;

('b) means pivotally connecting the outer end of the center cam to the cam block; and

(0) means extending between the center cam and the bed plate for supporting the center cam independently of the cam block.

2. A structure according to claim 1 wherein saidlastnamed means comprises a support rod loosely penetrating said cam plate and said cam block and extending between the bed plate and the lower surface of the center cam at its inner portion whereby downward movement of said cam plate in response to corresponding movement of the connecting arm effected by the pattern control mechanism will cause the cam block and stitch cam to move downwardly away from the center cam and sinkers to increase the length of stitches and the support rod will maintain the inner end of the center cam in operative position in the path of successive needles.

3. In a knitting machine having a needle cylinder and movable means including a stitch cam and a center cam for varying the lengths of the knitted stitches, the combination of:

(a) means effecting relative movement between the stitch cam and the center cam,

(b) means supporting the center cam at substantially a constant level, and

(0) means imparting rectilinear movement, in a direction parallel to the axis of the needle cylinder, to the stitch cam to vary the length of stitches in the knitted fabric.

4. A knitting machine having means for knitting a fabric including:

(a) a plurality of needles and a needle cylinder,

(b) a stitch cam for drawing down successive needles to form stitches,

(c) a center cam in advance of the stitch cam for moving successive needles into yarn engaging position and directing them under the stitch cam, and

(d) means imparting rectilinear movement, in a direction parallel to the axis of the needle cylinder, to the stitch cam independently of the center cam to vary the length of stitches.

5. A method of varying the length of stitches during knitting of a fabric on a circular knitting machine having a needle cylinder comprising the steps of:

(a) passing successive needles beneath a first cam while introducing yarn into the hooks of the needles,

(b) then passing said needles, in succession, beneath a second cam to draw stitches, and

(c) bodily reciprocating the second cam in a straightline motion parallel to the axis of the needle cylinder, to vary the length of stitches drawn while maintaining the first cam at substantially a constant level to continue drawing successive needles into yarn engaging position in advance of the second cam.

6. A knitting machine having means for knitting an elastic fabric including a plurality of needles, a stitch cam assembly; a pattern control mechanism, and a connecting arm extending between the pattern control mechanism and the stitch cam assembly for effecting reciprocal'movement to the stitch cam a'ssembly to vary the length of stit'chesknit into the fabric, said stitch cam assembly comprrsmg:

(a) a cam block,

(b) a stitch cam fixed to the block and extending therefrom into the path of successive needles to draw stitches during knitting,

(c) a center cam in advance of the stitch cam and positioned in the path of successive needles to move them into position to take the yarn from which the fabric is to be formed, and

((1) means supporting the center cam independently of the cam block to maintain the center cam at substantially a constant level during reciprocation of the stitch cam with the cam block and connecting arm in response to the pattern control mechanism.

7. A structure according to claim 6 wherein the cam surface on the center cam traversed by the needles extends beyond the proximal edge of the cam surface on the stitch cam when the stitch cam is moved to its extreme position away from the center cam.

8. A structure according to claim 6 wherein the center cam is pivotally connected to the cam block at a point remote from the path of the needles.

9. A structure according to claim 8 which includes resilient means carried by the cam block and normally urging the end portion of the center cam adjacent the path of the needles toward the cam block.

10. A structure according to claim 9 which includes a bed plate and wherein said means supporting the center cam comprises a supporting rod loosely penetrating the L1. cam block and extending between the bed plate and the end portion of the center cam adjacent the path of the needles.

11. A structure according to claim 10 wherein the support rod is axially adjustable whereby the end of the rod adjacent the center cam may be normally spaced-beneath the center cam a sufiicient distance to compensate for the upward pivotal movement of the portion of the center cam lying in the path of the needles as the cam block is dropped to draw long stitches.

References Cited by the Examiner UNITED STATES PATENTS 1,865,385 6/1932 Page 66-54 2,200,209 5/1940 Sheppard 6654 OTHER REFERENCES 603,177 8/1960 Canada.

DONALD W. PARKER, Primary Examiner.

P. C. FAW, Assistant Examiner. 

1. IN A CIRCULAR KNITTING MACHINE HAVING A PLURALITY OF RECIPROCABLE NEEDLES AND SINKERS COOPERATING WITH EACH OTHER FOR THE FORMATION OF STITCHES TO DEFINE A KNITTED FABRIC, SAID KNITTING MACHINE ALSO INCLUDING A BED PLATE, A CAM RING, PATTERN CONTROL MECHANISM AND A STITCH CAM ASSEMBLY OPERATIVE AT SELECTED POINTS DURING THE KNITTING OF THE FABRIC TO VARY THE LENGTH OF STITCHES IN THE FABRIC, SAID KNITTING MACHINE ALSO INCLUDING A CAM BLOCK FROM WHICH THE STITCH CAM AND CENTER CAM PROJECT INTO THE PATH OF THE NEEDLES AND A CONNECTING ARM EXTENDING BETWEEN THE PATTERN CONTROL MECHANISM AND THE CAM RING, THE COMBINATION OF MEANS FOR EFFECTING RELATIVE MOVEMENT BETWEEN THE STITCH CAM AND THE CENTER CAM, COMPRISING: (A) MEANS CONNECTING THE STITCH CAN TO THE CAM BLOCK FOR MOVEMENT WITH SAID CONNECTING ARM; (B) MEANS PIVOTALLY CONNECTING THE OUTER END OF THE CENTER CAM TO THE CAM BLOCK; AND (C) MEANS EXTENDING BETWEEN THE CENTER CAM AND THE BED PLATE FOR SUPPORTING THE CENTER CAM INDEPENDENTLY OF THE CAM BLOCK. 